Preheat oven to 350°F and line a cookie sheet with parchment paper. Set aside.
In a large mixing bowl, combine the flour, oats, baking soda, and salt. Set aside.
In a separate large bowl or stand mixer fitted with a paddle attachment, cream together the butter, brown sugar, and granulated sugar.
Add the egg, vanilla, and apple sauce to the butter/sugar mixture and mix well.
Add the flour mixture to the wet ingredients and mix just until combined.
Fold in the chocolate chips.
Use a medium cookie scoop (1.5 tablespoons) to drop scoopfuls of the dough onto the prepared cookie sheet.
Bake for 14 to 16 minutes or until the edges are golden brown.
Allow cookies to cool on the baking sheet for a few minutes before transfering them to a wire rack to cool completely.